U.S. patent application number 10/580265 was filed with the patent office on 2007-06-28 for method for producing organosilane.
This patent application is currently assigned to Central Glass Company, Limited. Invention is credited to Yoshihiro Muramatsu, Tsuyoshi Ogawa, Mitsuya Ohashi.
Application Number | 20070149798 10/580265 |
Document ID | / |
Family ID | 34631471 |
Filed Date | 2007-06-28 |
United States Patent
Application |
20070149798 |
Kind Code |
A1 |
Ogawa; Tsuyoshi ; et
al. |
June 28, 2007 |
Method for producing organosilane
Abstract
By reducing an organosilane represented by the formula (1),
SiX.sub.nR.sub.4-n (1) (wherein X represents a halogen or alkoxide,
n represents an integer of 1-3, and R represents an alkyl group or
aryl group), there is produced a corresponding organosilane
represented by the formula (2), SiH.sub.nR.sub.4-n (2) (wherein n
represents an integer of 1-3, and R represents an alkyl group or
aryl group). In this production method, an aromatic hydrocarbon
series organic solvent is used as a reaction solvent, and aluminum
lithium hydride is used as a hydrogenating agent.
Inventors: |
Ogawa; Tsuyoshi; (Yamaguchi,
JP) ; Muramatsu; Yoshihiro; (Yamaguchi, JP) ;
Ohashi; Mitsuya; (Yamaguchi, JP) |
Correspondence
Address: |
CROWELL & MORING LLP;INTELLECTUAL PROPERTY GROUP
P.O. BOX 14300
WASHINGTON
DC
20044-4300
US
|
Assignee: |
Central Glass Company,
Limited
5253, Oaza Okiube, Ube-shi
Yamaguchi
JP
755-0001
|
Family ID: |
34631471 |
Appl. No.: |
10/580265 |
Filed: |
November 9, 2004 |
PCT Filed: |
November 9, 2004 |
PCT NO: |
PCT/JP04/16558 |
371 Date: |
May 25, 2006 |
Current U.S.
Class: |
556/466 |
Current CPC
Class: |
C07F 7/0896
20130101 |
Class at
Publication: |
556/466 |
International
Class: |
C07F 7/00 20060101
C07F007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 26, 2003 |
JP |
2003-394883 |
Claims
1. A method for producing an organosilane, in which an organosilane
represented by the formula (1), SiX.sub.nR.sub.4-n (1) (wherein X
represents a halogen or alkoxide, n represents an integer of 1-3,
and R represents an alkyl group or aryl group) is reduced, thereby
producing a corresponding organosilane represented by the formula
(2), SiH.sub.nR.sub.4-n (2) (wherein n represents an integer of
1-3, and R represents an alkyl group or aryl group), which is
characterized in that an aromatic hydrocarbon series organic
solvent is used as a reaction solvent and that aluminum lithium
hydride is used as a hydrogenating agent.
2. A method for producing an organosilane according to claim 1,
which is characterized in that the reaction temperature is
40-120.degree. C.
3. A method for producing an organosilane according to claim 1,
which is characterized in that a substance that releases
AlCl.sub.4.sup.- ions in the organic solvent is used as a
catalyst.
4. A method for producing an organosilane according to claim 3,
which is characterized in that the catalyst is LiAlCl.sub.4.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for producing
organosilanes, which are useful for film-forming raw materials in
semiconductor production or for organic syntheses.
BACKGROUND OF THE INVENTION
[0002] Organosilanes, particularly methylsilane (CH.sub.3SiH.sub.3)
and trimethylsilane ((CH.sub.3).sub.3SiH), are raw material gases
that are useful as CVD film-forming materials in semiconductor
device production. Particularly in recent years, they attract
attention as raw material gases of low-dielectric-constant
insulating films. In methods for producing organosilanes, it is
general to use a method in which a reducing agent, such as aluminum
lithium hydride (LiAlH.sub.4), is used in a polar organic solvent,
such as diethyl ether (C.sub.2H.sub.5OC.sub.2H.sub.5),
dimethoxyethane (DME), diglyme (DGM) or tetrahydrofuran (THF). It
is superior in product purity and yield, too. Hitherto, it has been
considered that the reduction reaction by LiAlH.sub.4 occurs only
in a polar solvent and that the reaction does not occur in a
non-polar hydrocarbon series solvent such as hexane and heptane.
There have been no publications or the like having disclosures
other than reaction examples using polar solvents as reaction
solvents of organosilanes. Although a LiAlH.sub.4 reduction of
cyclohexanone has been tried in toluene solvent that is one of
aromatic hydrocarbon series organic solvents used in the present
invention, cyclohexanol that should be obtained by the reduction
has not been found (Non-patent Publication 1). It is generally
considered that AlH.sub.4.sup.- ion is produced in an organic
solvent by dissociation in LiAlH.sub.4 reduction, and this acts on
the reaction substance to generate the reaction. Therefore, it is
considered that the reaction proceeds only in a polar solvent that
can dissolve LiAlH.sub.4 and that the reaction does not occur since
it is not possible to dissolve LiAlH.sub.4 in a solvent that has
little polarity, such as toluene.
[0003] As an organosilane synthesis example using a polar solvent,
there is described a method for synthesizing (CH.sub.3).sub.3SiH
with a yield of 85% by reacting trimethylchlorosilane
((CH.sub.3).sub.3SiCl) with LiAlH.sub.4 under reflux at a
temperature of 86.degree. C. using DME solvent (Non-patent
Publication 2). Furthermore, there is described a method for
synthesizing (CH.sub.3).sub.3SiH with a yield of 91% by reacting
ethoxytrimethylsilane ((CH.sub.3).sub.3SiOC.sub.2H.sub.5) with
LiAlH.sub.4 at a temperature of 50-70.degree. C. using DGM solvent
(Patent Publication 1).
[0004] However, in these methods using polar solvents,
organosilanes that are in solvation remain in the residual liquids
after the termination of the reactions. The difficulty in their
recovery caused lowering of yield. In the case of treating the
reaction residual liquid, it was difficult to recover the solvent
by the treatment with water, since all of the solvents other than
diethyl ether are water-soluble. Even in the case of using a method
of recovering the solvent from the reaction residual liquid through
evaporation, a separation from the residue was difficult due to
high polarity of the solvent, and the solvent recovery use was
extremely difficult. [0005] Patent Publication: WO 01/58908 [0006]
Non-patent Publication 1: J. Chem. Res. (S), 1, 24 (1990) [0007]
Non-patent Publication 2: J. Amer. Chem. Soc., 83, 1916 (1961)
SUMMARY OF THE INVENTION
[0008] It is an object of the present invention to provide a method
for producing an organosilane of high purity with high yield and
with good productivity, while solving a problem possessed by
conventional polar solvents.
[0009] According to the present invention, there is provided a
method for producing an organosilane, in which an organosilane
represented by the formula (1), SiX.sub.nR.sub.4-n (1) (wherein X
represents a halogen or alkoxide, n represents an integer of 1-3,
and R represents an alkyl group or aryl group) is reduced, thereby
producing a corresponding organosilane represented by the formula
(2), SiH.sub.nR.sub.4-n (2) (wherein n represents an integer of
1-3, and R represents an alkyl group or aryl group),
[0010] which is characterized in that an aromatic hydrocarbon
series organic solvent is used as a reaction solvent and that
aluminum lithium hydride is used as a hydrogenating agent.
DETAILED DESCRIPTION
[0011] According to the method of the present invention, it is
possible to easily recover the solvent used in the reaction and to
produce an organosilane of high purity with high yield and good
productivity.
[0012] According to the present invention, there is used a slightly
polar solvent that is insoluble in water. Therefore, it is possible
to easily recover the solvent by subjecting the reaction residual
liquid to washing with water and to liquid separation. Since it has
almost no polarity, it is possible to recover almost the total
amount of an organosilane produced by the reaction, and it can be
produced with very high yield. Furthermore, aromatic hydrocarbons
are generally high in boiling point. Therefore, the amount of the
solvent accompanied with the produced organosilane is small, and it
is possible to relatively easily achieve ultra high purity that is
required in case that it is used as a semiconductor film-forming
material gas.
[0013] According to the present invention, it is possible to
produce an organosilane by reacting an organohalosilane or the
like, which is a raw material, with LiAlH.sub.4 in an aromatic
hydrocarbon series solvent that is a slightly polar solvent under a
condition of 40-120.degree. C. In this case, it was found to be a
self-catalyst reaction in which LiAlCl.sub.4 produced by
by-production becomes a catalyst. It was found that the reaction
rate of the initial stage increases remarkably by adding
LiAlCl.sub.4 particularly at the start of the reaction and thereby
an organosilane can safely and stably be produced.
[0014] In the following, the present invention is exemplarily
described in detail. An organohalosilane or the like that is used
as the raw material in the present invention is one represented by
the formula (1), SiX.sub.nR.sub.4-n (1) wherein X represents a
halogen or alkoxide, n represents an integer of 1-3, and R
represents an alkyl group or aryl group. Examples of R are alkyl
groups such as methyl group, ethyl group, propyl group and
isopropyl group, and aryl groups. In case that a plurality of R
exist, these may be the same or different from each other. As X, it
is possible to use fluoro group, chloro group, bromo group, iodo
group, methoxy group, ethoxy group and the like. In general, one
having a chloro group(s), which is easily available and low in
price, is preferably usable.
[0015] It suffices that the solvent to be used is a hydrocarbon
series solvent containing an aromatic ring, but it must be one that
can dissociate and dissolve AlCl.sub.4.sup.- ions. Specifically, it
is possible to cite benzene, toluene, xylene, ethylbenzene,
butylbenzene, and anisole.
[0016] In order to make the reaction proceed smoothly, the addition
of catalyst is essential in the present invention. That is, in case
that the catalyst does not exist, the reducing power of LiAlH.sub.4
is low and the reaction is extremely slow in an aromatic
hydrocarbon series solvent that is low in polarity. The catalyst is
not particularly limited, as long as it is a substance that
releases AlCl.sub.4.sup.- ions. Specifically, LiAlCl.sub.4,
NaAlCl.sub.4, KAlCl.sub.4 and the like are cited. LiAlCl.sub.4 is
particularly preferable. In case that a chloride is used as the
organohalosilane or the like of the raw material, it becomes a
self-catalyst reaction, since LiAlCl.sub.4 is produced as a
by-product as the reaction proceeds. Therefore, if the reaction is
conducted with no catalyst, the reaction rate is slow at the
initial stage of the reaction, and the reaction rate increases
remarkably as the reaction proceeds. As a result, in case that the
introduction rate of the chloride of the raw material is high, it
is extremely dangerous since the reaction often proceeds at once
and crashes. AlCl.sub.3 is famous as a reaction catalyst of
LiAlH.sub.4. However, it hardly acts as a catalyst in the present
invention.
[0017] As the catalyst, LiAlCl.sub.4 itself may be used, and a
mixture of LiCl and AlCl.sub.3 (1:1), which is easily available,
may also be used. In case that a chloride is used as the raw
material, it is also possible to reuse a part of LiAlCl.sub.4 that
has been produced in the reaction residual liquid. It is preferable
to add the catalyst to be greater than solubility in the solvent.
For example, in case that toluene is used as the solvent, it is
added preferably in 0.02 g/ml or greater.
[0018] In the present invention, the reaction is conducted at a
reaction temperature of 40.degree. C.-120.degree. C., preferably
60-100.degree. C. If it is less than 40.degree. C., the reduction
capacity is low, and the reaction becomes very slow. If it exceeds
120.degree. C., danger is caused due to the occurrence of
decomposition reaction of LiAlH.sub.4.
[0019] After the termination of the reaction, it is possible to
recover the organosilane that is dissolved in the solvent by
heating or depressurizing the reactor. The dissolved organosilane
is not subjected to solvation. Therefore, it is possible to recover
the total amount of the dissolved organosilane. In the case of
using a chloride as the raw material, the reaction residual liquid
is immediately separated into two layers of the solvent layer and
the residue layer of LiAlCl.sub.4. Therefore, it can easily be
separated into the residue and the solvent by liquid separation.
LiAlCl.sub.4 is dissolved in the recovered solvent. By using this
again in the reaction, it becomes unnecessary to newly add the
catalyst.
[0020] It is possible to easily recover the pure solvent by
conducting washing with hydrochloric acid or washing with water and
then the liquid separation in the treatment of the residual
liquid.
[0021] In the following, the present invention is specifically
described by examples, but the present invention is not limited to
the following examples.
EXAMPLE 1
[0022] A 500 ml glass flask equipped with a reflux condenser was
replaced with helium gas. The flask was charged with LiAlH.sub.4 of
1.16 g (0.031 mol) and toluene of 30 ml, followed by stirring,
increasing the temperature to 80.degree. C., and then adding
(CH.sub.3).sub.3SiCl of 14ml (0.110 mol) in a dropwise manner by 10
min. Gas generation did almost not occur immediately after the
dropping, but gas generation occurred gradually with the dropping.
At a point when 1/3 was dropped, an abrupt bubbling was observed.
The generated gas was passed through the reflux condenser, and then
the total amount was collected in a trap chilled by liquid
nitrogen, followed by measuring the weight. The collected gas was
identified and quantified by a gas chromatograph and a gas
chromatograph-mass spectrometer. The obtained gas was
(CH.sub.3).sub.3SiH. Purity was 96.9 vol %, and yield was
92.5%.
EXAMPLE 2
[0023] The reaction was conducted by the same method as that of
Example 1, except in that the flask was charged with LiAlCl.sub.4
of 0.6 g (0.004 mol) as the catalyst together with LiAlH.sub.4. Gas
generation was found from immediately after the dropping of
(CH.sub.3).sub.3SiCl. An abrupt bubbling was not found, and the
reaction proceeded mildly. The collected gas was
(CH.sub.3).sub.3SiH. Purity was 98.1 vol %, and yield was
92.7%.
EXAMPLE 3
[0024] The reaction was conducted by the same method as that of
Example 1, except in that the flask was charged with AlCl.sub.3 of
0.5 g (0.004 mol) and LiCl of 0.13g (0.003 mol) as the catalyst
together with LiAlH.sub.4. Gas generation was found from
immediately after the dropping of (CH.sub.3).sub.3SiCl. An abrupt
bubbling was not found, and the reaction proceeded mildly. The
collected gas was (CH.sub.3).sub.3SiH. Purity was 97.8 vol %, and
yield was 94.4%.
EXAMPLE 4
[0025] The reaction was conducted by the same method as that of
Example 1, except in that 30 ml of the liquid of the solvent layer
of the reaction residual liquid were used in place of toluene. Gas
generation was found from immediately after the dropping of
(CH.sub.3).sub.3SiCl. An abrupt bubbling was not found, and the
reaction proceeded mildly. The collected gas was
(CH.sub.3).sub.3SiH. Purity was 92.4 vol %, and yield was
94.3%.
EXAMPLE 5
[0026] The reaction was conducted by the same method as that of
Example 3, except in that 30 ml of xylene were used in place of
toluene. Gas generation was found from immediately after the
dropping of (CH.sub.3).sub.3SiCl. An abrupt bubbling was not found,
and the reaction proceeded mildly. The collected gas was
(CH.sub.3).sub.3SiH. Purity was 96.3 vol %, and yield was
95.4%.
EXAMPLE 6
[0027] The reaction was conducted by the same method as that of
Example 3, except in that 4 ml (0.037 mol) of CH.sub.3SiCl.sub.3
were added in a dropwise manner in place of (CH.sub.3).sub.3SiCl.
Gas generation was found from immediately after the dropping of
CH.sub.3SiCl.sub.3. An abrupt bubbling was not found, and the
reaction proceeded mildly. The collected gas was CH.sub.3SiH.sub.3.
Purity was 96.8 vol %, and yield was 93.1%.
EXAMPLE 7
[0028] The reaction was conducted by the same method as that of
Example 3, except in that the reaction temperature was 40.degree.
C. Gas generation was found from immediately after the dropping of
(CH.sub.3).sub.3SiCl, but the amount of the gas generated was
small. Even after the termination of the dropping, the gas
generation continued. The reaction terminated 6 hr later. The
collected gas was (CH.sub.3).sub.3SiH. Purity was 94.8 vol %, and
yield was 81.3%.
EXAMPLE 8
[0029] The reaction was conducted by the same method as that of
Example 3, except in that the reaction temperature was 120.degree.
C. Gas generation was found from immediately after the dropping of
(CH.sub.3).sub.3SiCl. An abrupt bubbling was not found, and the
reaction proceeded mildly. The collected gas was
(CH.sub.3).sub.3SiH. Purity was 93.5 vol %, and yield was
78.1%.
EXAMPLE 9
[0030] The reaction was conducted by the same method as that of
Example 3, except in that the initial temperature was 25.degree. C.
Gas generation did almost not occur until the termination of the
dropping of (CH.sub.3).sub.3SiCl. When the temperature was
increased to 80.degree. C. with stirring, an abrupt bubbling was
observed 5 min later (80.degree. C.). Therefore, the generated gas
was collected in a trap. The collected gas was (CH.sub.3).sub.3SiH.
Purity was 93.5 vol %, and yield was 91.1%.
EXAMPLE 10
[0031] A 1.5 L stainless steel reactor equipped with a reflux
condenser was replaced with helium gas. The reactor was charged
with LiAlH.sub.4 of 24.85 g (0.655 mol), AlCl.sub.3 of 5.02 g
(0.038 mol), LiCl of 1.60 g (0.038 mol) and toluene of 321 ml,
followed by stirring, increasing the temperature to 80.degree. C.,
and then adding (CH.sub.3).sub.3SiCl of 300 ml (2.364 mol) in a
dropwise manner by 3 hr. Gas generation was found from immediately
after the dropping. An abrupt bubbling was not found, and the
reaction proceeded mildly. The collected gas was
(CH.sub.3).sub.3SiH. Purity was 98.0 vol %, and yield was 96.6%.
300 ml of 1% hydrochloric acid were added to the reaction residual
liquid after the reaction, and the aqueous layer was taken out from
the lower layer. The organic layer of the upper layer was obtained
318 ml. It was toluene having a purity not lower than 99%.
COMPARATIVE EXAMPLE
[0032] The reaction was conducted by the same method as that of
Example 1, except in that 30 ml of tetrahydrofuran (THF) were used
as the solvent in place of toluene and that the reaction
temperature was room temperature. Gas generation was found from
immediately after the dropping of (CH.sub.3).sub.3SiCl. An abrupt
bubbling was not found, and the reaction proceeded mildly. The
collected gas was (CH.sub.3).sub.3SiH. Purity was 76.2 vol %, and
yield was 71.4%.
* * * * *